Wiring substrate for small electronic component and manufacturing method

Abstract

A wiring substrate for used in a small electronic component. The wiring substrate comprises: an insulating substrate; and a conductive land portion which is formed on a first surface of the insulating substrate and on which an electronic element is to be mounted via conductive adhesive to electrically couple an electrode of the electronic element with the conductive land portion. The thickness of the peripheral portion of the conductive land portion which surrounds the electronic element is thicker than that of the central portion of the conductive land portion. The insulating substrate may also have a conductive land portion which is formed on a second surface of the insulating substrate and which is electrically coupled with the conductive land portion formed on the first surface of the insulating substrate via a through hole penetrating through the insulating substrate.

What is claimed is:  
     
         1 . A wiring substrate comprising: 
 an insulating substrate; and    a conductive land portion which is formed on a first surface of the insulating substrate and on which an electronic element is to be mounted via conductive adhesive to electrically couple an electrode of the electronic element with the conductive land portion;    wherein the thickness of the peripheral portion of the conductive land portion which surrounds the electronic element is thicker than that of the central portion of the conductive land portion.    
     
     
         2 . A wiring substrate as set forth in  claim 1 , wherein the insulating substrate further has a conductive land portion which is formed on a second surface of the insulating substrate and which is electrically coupled with the conductive land portion formed on the first surface of the insulating substrate via a through hole penetrating through the insulating substrate, the second surface being opposite to the first surface.  
     
     
         3 . A wiring substrate as set forth in  claim 2 , wherein the conductive land portion formed on the second surface of the insulating substrate is used for surface mounting an electronic component which is fabricated by using the wiring substrate.  
     
     
         4 . A wiring substrate as set forth in  claim 1 , wherein the insulating substrate has a large size conductive land portion on which the electronic element is to be mounted and at least one small size conductive land portion which is to be electrically coupled with the electronic element via conductive wire or wires.  
     
     
         5 . A method of manufacturing a wiring substrate comprising: 
 preparing an insulating substrate;    applying a photo resist film on the insulating substrate and patterning the photo resist film to form an opening portion to expose a portion of the insulating substrate on which a conductive land portion is to be formed;    forming a conductive film on the portion of the insulating substrate which is exposed via the opening portion by using electroless plating; and    electro plating the insulating substrate which is electroless plated, in plating solution containing plating additive which improves embedding characteristics, and forming an electro plated conductive film portion on the conductive film portion formed by electroless plating;    wherein the thickness of the peripheral portion of the electro plated conductive film portion is thicker than that of the central portion thereof.    
     
     
         6 . A method of manufacturing a wiring substrate comprising: 
 preparing an insulating substrate;    forming a conductive land area on the insulating substrate;    etching the central portion of the conductive land area partially in the thickness direction, thereby, forming a conductive land portion which has a swelled portion on the periphery thereof.    
     
     
         7 . A method of manufacturing a wiring substrate as set forth in  claim 6 , wherein the forming the conductive land area comprises: 
 forming a thick conductive film on the insulating substrate;    applying a photo resist film on the thick conductive film on the insulating substrate and patterning the photo resist film to expose portion or portions of the thick conductive film on the insulating substrate where a conductive land portion is not to be formed; and    etching the thick conductive film by using the patterned photo resist film as a mask and forming the conductive land portion on the insulating substrate; and    wherein the forming a conductive land portion which has a swelled portion on the periphery thereof comprises:    forming a second photo resist film having an opening on the conductive land portion, but the size of the opening is slightly smaller than that of the conductive land portion and the peripheral portion of the conductive land portion is covered by the second photo resist film; and    etching the conductive land portion by using the second photo resist film as a mask such that the conductive land portion is partially etched away in the thickness direction.    
     
     
         8 . An electronic component comprising: 
 a wiring substrate having an insulating substrate, and a conductive land portion formed on a first surface of the insulating substrate, the thickness of the peripheral portion of the conductive land portion being thicker than that of the central portion of the conductive land portion; and    an electronic element mounted on the central portion of the conductive land portion via conductive adhesive to electrically couple an electrode of the electronic element with the conductive land portion.    
     
     
         9 . An electronic component as set forth in  claim 8 , wherein the insulating substrate further has a conductive land portion which is formed on a second surface of the insulating substrate and which is electrically coupled with the conductive land portion formed on the first surface of the insulating substrate via a through hole penetrating through the insulating substrate, the second surface being opposite to the first surface.  
     
     
         10 . An electronic component as set forth in  claim 9 , wherein the conductive land portion formed on the second surface of the insulating substrate is used for surface mounting an electronic component which is fabricated by using the wiring substrate.  
     
     
         11 . An electronic component as set forth in  claim 8 , wherein the insulating substrate has a large size conductive land portion on which the electronic element is mounted and at least one small size conductive land portion which is electrically coupled with the electronic element via conductive wire or wires.  
     
     
         12 . An electronic component as set forth in  claim 8 , wherein the insulating substrate is covered by an encapsulation resin portion on the side the electronic element is mounted.